1. Technical Field
This invention relates to the field of providing call handoff in a wireless environment such as a neighborhood cordless service that provides service at a flat rate wherein there is no air time charge for calls made within a home neighborhood zone or subscribed-to visiting neighborhood zone(s).
2. Description of the Related Arts
It is known to provide wireless services for a fixed fee and to charge additional air time fees for each period of time that a subscriber to the wireless services is using the radio frequency spectrum. Such services were initiated in the 1970's as analog wireless services and have become digital over time, for example, the relatively new digital personal communications services (DPCS).
It has been known up until recently to permit users to have cordless telephone apparatus comprising a base station and a mobile unit such that the mobile unit may communicate with the base station over limited distances of several hundred feet. Recently, in the United States, however, a band of frequencies has been made available in the 900 MHZ range for providing cordless telephone service where the mobile station can be as far removed from the base station portion of the station apparatus by as much as one mile under optimal conditions. Consequently, a user would not have to pay for air time charges as in wireless services such as personal communications services if a mobile station is confined within one mile radius of the typically home-located base station.
Fixed wireless subscriber loop services are also known. Equipment for providing such services is available from suppliers such as Diva Communications and OptoPhone Systems. The fixed wireless subscriber loop concept has been used successfully to provide telephone services to remote, for example, mountainous regions. To provide a copper wire subscriber loop to such customers can cost hundreds of thousands of dollars per subscriber. Subscribers to a fixed wireless subscriber loop system have an antenna mounted to their home or business and receive an equivalent of wired services over a wireless link to an antenna site, for example, on the top of the mountain. Service can be provided for a fixed rate, the copper subscriber wired loop eliminated and no air time charges are charged.
There is still a need in the art for a wireless service that would permit a mobile subscriber to roam within a zone close to their home in the same way as a 900 MHZ cordless customer is free to carry their cordless phone from room to room. A mobile subscriber should be able to roam and also move from one zone to another or make calls from non-contiguous zones without having to pay for air time charges. In today's cellular environment, airtime is charged. The current fee structure thus has very little incentive for customers to continue use their cellular phones when they have access to a home-based landline phone. In order to achieve the objectives of one phone, one number anytime and anywhere communications, it is imperative that a neighborhood or local ‘cordless type’ of services be provided to all the public cellular/PCS subscribers and with incentive to use the same PCS phone in the home/office and around the neighborhood area without air time charges. A subscriber should not lose a call in progress as they move from one subscribed-to zone to another adjacent subscribed zone, and should have the opportunity to switch automatically to known DPCS services and pay air time charges should they so choose.
There is further a need for providing call hand-off in such a proposed wireless service. For example, there is a need to provide call hand-off between cells in such a proposed network and between such a proposed network and an existing conventional network such as a conventional macro-cellular wireless network.